The objective of this study is to determine the relative efficacy of: 5-FU, 5-FU+ Leucovorin, 5-FU+ Levamisole and 5-FU + Leucovorin + levamisole with pelvic RT in the treatment of stages B-2 and C (TNM stage II and III) rectal cancer. End points will include local recurrence rates, probability of distant metastases, disease free survival rates and overall survival. (RTOG 90-14)